Structure and cytotoxicity of new polyhydroxylated sterols from the Caribbean gorgonian Plexaurella grisea

The gorgonian Plexaurella grisea contains the new steroids 9-hydroxygorgost erol (1), 9,11 alpha ,14-trihydroxygorgosterol (2), 5 beta ,6 beta -epoxyer gost-24(28)-ene-3 beta ,7 beta -diol (3), ergost-24(28)-ene-3 beta ,5 alpha ,6 beta ,7 beta -tetrol (4), an unseparable 1:1 mixture of the epimers (25 R) and (25S)-26-acetoxy-3 beta ,5 alpha -dihydroxyergost-24(28)-en-6-one (5 /6), and seven related, known compounds (7-13). The structures of these new compounds were defined by spectroscopic analysis. All the compounds (1-13) isolated from P. grisea were tested against P 388, A 549, and HT 29 tumor cell lines. Compounds 3, 5/6, and 12 exhibited selective activity against t he HT 29 cell line (ED50 = 0.1 mug/ml). (C) 2001 Elsevier Science Inc. All rights reserved.